The Dongen Formation is a geologic formation in the subsurface

Subsurface

Subsurface is the seventh studio album by British progressive metal band Threshold. The album was released in August 2004, and received an Album of the Month award in several European music magazines....

 of the Netherlands

Netherlands

The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

. The formation consists of early Eocene

Eocene

The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

 marine

Marine (ocean)

Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

 clay

Clay

Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...

 and sand

Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...

. It is named after the town of Dongen

Dongen

Dongen is a municipality and a village in the southern Netherlands. In the past it was home to a profitable Leather industry, to which a few old shoe factories in the town's older sections still testify. The town is formed near a small river called "Donge" , the water of which was used extensively...

 in North Brabant

North Brabant

North Brabant , sometimes called Brabant, is a province of the Netherlands, located in the south of the country, bordered by Belgium in the south, the Meuse River in the north, Limburg in the east and Zeeland in the west.- History :...

.

Lithology and stratigraphy

The Dongen Formation consists predominantly of marine clay, alternated with layers of fine sand or glauconiferous

Glauconite

Glauconite is an iron potassium phyllosilicate mineral of characteristic green color with very low weathering resistance and very friable.It crystallizes with a monoclinic geometry...

 marl

Marl

Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and aragonite. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay...

. The clay can also contain glauconite and locally thin layers of tuffite

Tuffite

Tuffite is a tuff containing both pyroclastic and detrital materials, but predominantly pyroclasts ....

 or loam

Loam

Loam is soil composed of sand, silt, and clay in relatively even concentration . Loam soils generally contain more nutrients and humus than sandy soils, have better infiltration and drainage than silty soils, and are easier to till than clay soils...

 can occur.

The formation is subdivided into four members:

• the Asse Member, clay with locally sandy layers, glauconite or/and nummulite
  Nummulite
  thumb|left|250px|Fossil Nummulites in [[Urbasa]], [[Basque Country |Basque Country]]A nummulite is a large lenticular fossil, characterized by its numerous coils, subdivided by septa into chambers. They are the shells of the fossil and present-day marine protozoan Nummulites, a type of foraminiferan...
  
  s;
• the Brussels Member, fine glauconiferous sand, locally calcareous;
• the Ieper Member, clay with layers of marl and limestone
  Limestone
  Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
  
  ;
• the Oosteind Member, clay with sand and tuffite layers.

The base of the formation is often formed by a tuffite layer.

The Dutch Dongen Formation correlates with the Belgian Ieper Group

Ieper Group

The Ieper Group is a group of rock strata in the subsurface of northwest Belgium. The group is subdivided into three marine formations, all formed during the Ypresian, a single age of the geologic timescale...

 and Zenne Group

Zenne Group

The Zenne Group is a group of rock strata in the subsurface of central and northwest Belgium. The group consists of three formations, all from the Ypresian and Lutetian ages...

. All of these units are marine sands and clays from the Ypresian

Ypresian

In the geologic timescale the Ypresian is the oldest age or lowest stratigraphic stage of the Eocene. It spans the time between and , is preceded by the Thanetian age and is followed by the Eocene Lutetian age....

 (55.8 - 48.6 million years ago) and Lutetian

Lutetian

The Lutetian is, in the geologic timescale, a stage or age in the Eocene. It spans the time between and . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it is sometimes referred to as the Middle Eocene subepoch...

 (48.6 - 40.4 million years ago) ages, when the eustatic sea level

Sea level

Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...

 was relatively high after the Paleocene–Eocene Thermal Maximum. The sea level was so high that the North Sea

North Sea

In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

 was connected with the Paris Basin

Paris Basin

Paris Basin may refer to:*As a hydrological basin, it is largely the basin of the River Seine* Paris Basin , the geological basin...

 to the south and all of the Netherlands and most of Belgium and northern France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 was covered by shallow seas.

Dutch stratigraphers put the Dongen Formation together with the older Landen Formation

Landen Formation

The Landen Formation is a lithostratigraphic unit in the subsurface of the Netherlands. This formation shares its name with the Belgian Landen Group, but the Belgian unit is thinner and has different definitions...

 in the Lower North Sea Group

Lower North Sea Group

The Lower North Sea Group is a group of geologic formations in the subsurface of the Netherlands and adjacent parts of the North Sea....

. The top of the Dongen Formation is formed by a nonconformity

Nonconformity

Nonconformity may refer to:* Nonconformity , a memoir by Nelson Algren, published posthumously in 1992* Nonconformity , a term in quality management* A type of unconformity in geology...

, over which younger formations, such as the Oligocene

Oligocene

The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...

 Rupel Formation

Rupel Formation

The Rupel Formation is a geologic formation in the subsurface of the Netherlands that consists of Oligocene marine sands and clays. The Rupel Formation is part of the Middle North Sea Group and correlates exactly with the Belgian Rupel Group....

 or the Miocene

Miocene

The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

 Breda Formation

Breda Formation

The Breda Formation is a geologic formation in the subsurface of the Netherlands. The formation consists of marine glauconiferous sands and clays that were deposited during the Miocene epoch...

, are found.

Literature

(eds.); 1993: Stratigraphic nomenclature of the Netherlands, revision and update by RGD and NOGEPA, Mededelingen Rijks Geologische Dienst 50, pp. 1–39.

External links

; 2003: Formatie van Dongen, TNO

Netherlands Organisation for Applied Scientific Research

Nederlandse Organisatie voor Toegepast Natuurwetenschappelijk Onderzoek or TNO is a not-for-profit organization in the Netherlands that focuses on applied science. The main office of TNO is located in Delft...

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